The present invention relates to a minimally invasive method and applicator tool for implanting cardiac cardioversion/defibrillation electrodes, especially wire patch electrodes and cardiac electrodes similar to those set out in the aforementioned concurrently filed application.
Epicardial cardioversion/defibrillation electrodes most often require major thoracic surgery (median sternotomy or thoracotomy) for implantation. This highly invasive surgical procedure leads to substantial patient morbidity. By eliminating the need for these invasive surgical procedures, implantable defibrillation therapy acceptance for certain patient populations may increase.
For electrode configurations not employing endocardial electrode(s), two separate epicardial electrodes of opposite polarity (normally located on the left and right ventricles) are required for efficacious defibrillation therapy. Recently, much emphasis has been placed on reducing post-operative patient morbidity by limiting the invasiveness of requisite surgical procedures for application of internal defibrillation therapy. The present invention addresses these problems by allowing intrathoracic implantation of conventional wire mesh patch electrodes through small (1-2 cm) chest wall defects (normally intercostal).
Prior attempts to utilize a special tool for patch electrode introduction are exemplified in U.S. Pat. No. 4,291,707--Heilman and U.S. Pat. No. 4,270,549--Heilman et al. Specifically, reference is made to FIG. 4 in the '707 patent and FIGS. 4 and 7 in the '549 patent. Although generally effective, these prior attempts were complicated by (1) maintenance of a substantially planar patch orientation which requires a long cutaneous incision (more invasive) for introduction, (2) lack of remotely actuatable disengagement mechanism, (3) potential tissue trauma during tool extraction.
Probably the most significant disadvantage to these prior attempts is that the electrodes could not be atraumatically introduced through a small circular chest wall defect. Consequently, either large cutaneous incisions were required or the patches were severely and irreparably deformed during introduction.